roblem: Solve c^2-4c-45=0
What is the answer to c^2-4c-45=0
c^2 - 4c - 45 = 0
We are fortunate here, because the factors of
45 are 5 and 9. They just happen to have a
difference of 4. So we factor the left side:
(c - 9)(c + 5) = 0
Setting each factor to zero, we solve for c.
c - 9 = 0
c = 9
and
c + 5 = 0
c = -5
Answer: c = 9 and c = -5